Fig. 3. (Top ) Representative trace depicting the effect of the tyrosine kinase inhibitor tyrphostin 23 (Tyr; 100 μm) on capacitative calcium entry. After depletion of sarcoplasmic reticulum Ca2+stores with thapsigargin, capacitative calcium entry was compared in the absence or presence of tyrphostin 23, which was added to the superfusion buffer 5 min before restoring extracellular Ca2+concentration ([Ca2+]o). (Bottom ) Summarized data showing the inhibitory effect (*P < 0.05) of tyrphostin 23 on capacitative Ca2+entry. This inhibitory effect of tyrphostin 23 was entirely reversible (n = 7 cells).